Hot channel system

ABSTRACT

A valve gated hot runner system that includes a single movable plate (or movable frame) that retains multiple valve pins. A linear actuator is coupled to rigid transmission elements that convey a linear motion from the actuator to several rotary components via a direct or indirect contact between at least a portion of the rigid transmission elements and the rotary components. The rigid transmission elements and the rotary components are connected to a common plate. The rotary components are further coupled to the movable plate (frame) and through their full rotation or turning lift or translate the movable plate (frame) with the valve pins to open and close the communication between hot runner nozzles and corresponding mold cavities. The actuator can be electrical, electro-magnetic, pneumatic or hydraulic.

RELATED APPLICATIONS

This application claims the benefit of priority to internationalapplication PCT/EP2013/000572 filed Feb. 27, 2013 which claims thebenefit of priority to German Application No. 10 2012 003 574.8 filedFeb. 27, 2012 the disclosures of which are incorporated herein byreference in their entirety as if fully set forth herein.

FIELD

The present invention relates to hot runner systems for injectionmolding and associated methods for injection molding. More particularly,the present invention relates to valve gated hot runner systems usingmovable plates and associated methods for injection molding using suchplates.

BACKGROUND

Hot runner systems using a common plate to actuate valve pins are known.In some documents these plates are called synchro-plates. In some casesone synchro plate may be used to actuate all the valve pins and in someother cases several plates may be used to actuate clusters of valve pinsin a synchronized manner. By using such plates all of the valve pins orjust several valve pins are moved simultaneously into the known openposition and closing position. This ensures that equal amounts of amolten material are delivered into at least two mold cavities having thesame volume. This also means that the mold may have mold cavities of thesame volume to form identical parts or the mold may have clusters ofmold cavities having equal or unequal volumes to form parts havingdifferent volumes that are called family mold cavities.

There is a need to better control the movement of the plates retainingthe valve pins, especially to make sure that there is no delay betweenthe movement of the plate and the actual movement of the actuators thatdrive the plate. This is a problem when belts or other non-rigidelements are used to convey the movement from the actual actuator

There is also a need to prevent or minimize any deformations of theelements that provide connections between the plate and the actuator ofthe plate to ensure long life of the system and faster cycle time.

SUMMARY

In an embodiment of the invention a valve gated hot runner systemsincludes a single movable plate (or movable frame) that retains multiplevalve pins. A linear actuator is coupled to rigid transmission elementsthat convey a linear motion from the actuator to several rotarycomponents via a direct or indirect contact between at least a portionof the rigid transmission elements and the rotary components. The rigidtransmission elements and the rotary components are connected to acommon plate. The rotary components are further coupled to the movableplate (frame) and through their full rotation or turning lift ortranslate the movable plate (frame) with the valve pins to open andclose the communication between hot runner nozzles and correspondingmold cavities.

In an embodiment of the invention the rigid elements are gear racks andthe rotary elements are gear pinions engaged to each other.

In an embodiment of the invention the rigid elements are levers andthrust rods and the rotary elements are gears.

In an embodiment of the invention the rotary elements are ball screws.

In an embodiment of the invention the rotary elements are cam-tracks.

In an embodiment of the invention the valve pins have a cylindricalsection on their free end allowing the valve pin to enter into the moldcavity outlet openings (or mold gate orifice) with accurate alignment atdifferent locations relative to the mold cavity. In an embodiment of theinvention each valve pin has at least two tips corresponding to twoseparate mold cavity outlet openings.

In an embodiment of the invention each nozzle has at least two separatevalve pins that are used to inject into two separate mold cavities, thetwo valve pins being movable in different directions.

In an embodiment of the invention it is thereby advantageously possiblefor the support plate on the motion converter devices to be supportedagainst the mounting at a distance from the edge of the support plate sothat also in the case of large support plates comprising a plurality ofvalve pins and/or adjusting means, flexural deformations of the supportplate can be largely prevented when quickly opening and closing the hotrunner nozzles. Thus, a large number of valve pins can be synchronouslydisplaced together at high dynamics with just one actuating drive. Sincethe sliding mechanism and the motion converter device exhibiting theinclined planes enable a mechanically stable or rigid drive connectionbetween the actuating drive and the support plate, the linear movementproduced by means of the actuating drive can be transmitted uniformly tothe individual motion converter devices and from these to thespaced-apart positions of the support plate. A simultaneous opening andclosing of all of the valve pins is thus possible even given highlydynamic displacing of the valve pins.

In an embodiment of the invention, the actuator is designed as anelectric motor and/or controllable by means of a suitable drive controldevice such that the valve pins can be positioned in at least one thirdposition disposed between a first position and a second position and canbe held as needed in said third position. The valve pins can then bebrought as needed into the at least one third position during theinjection molding process in order to better control the melt flow. Thevalve pins can thus be axially displaced in controlled manner. The hotrunner nozzles can thus have a relatively small open cross section ine.g. the third position such that the melt can be injected into the moldcavity at a high flow rate, which has the advantage of high frictionalheat simultaneously developing in the nozzle opening which benefits andsustains the flow process. When the mold cavities are almost full ofinjection molding material and it begins on the one hand to solidify andon the other to shrink, however, a dwell pressure phase can be initiatedin which the valve pins retract and the open cross section therebyenlarges so that despite the now less favorable conditions, injectionmolding material can be re-pressed.

In an embodiment of the invention, the valve pins comprise a cylindricalsection at their respective free end region distant from the supportplate which preferably interacts in each case with a respectivelycorresponding valve seat of the respective hot runner nozzle such thatit is closed in both the second position as well as in the thirdposition of the valve pins. Prior to the molded parts being removed fromthe mold cavities, the valve pins can then be moved back into the thirdposition from their closed position or final position respectively inwhich they are arranged in the second position in which they protrudesomewhat into the mold cavity in order for the molded parts to then beremoved from the mold cavities. This thus prevents the valve pins fromcoming into contact with the molded parts when they are being removedfrom the molds and leaving marks on the surfaces of the molded parts.The positioning of the valve pins in the at least three differentpositions additionally affords a clean gate mark.

In an embodiment of the invention, at least two hot runner nozzles haveoutlet openings pointing in different directions and valve pins pointingin different directions, wherein said valve pins are in drive connectionwith an adjusting means such that the closing force is transmittablefrom the adjusting means to the valve pins. It is thereby possible tosimultaneously displace a plurality of valve pins with one adjustingmeans. The valve pins are thereby arranged transverse and in particularat right angles to the adjusting means. The adjusting means can be ofpin or rod configuration.

In an embodiment of the invention, the reciprocating apparatus on themounting comprises a third rotary element in drive connection with thefirst thrust rod rotatably mounted about a third axis and a fourthrotary element in drive connection with the second thrust rod rotatablymounted about a fourth axis such that the third and fourth axes are ineach case at a parallel distance to the first and second axes and thethird rotary element is in drive connection by way of a third motionconverter device comprising at least one third inclined plane and thefourth rotary element is in drive connection by way of a fourth motionconverter device comprising at least one fourth inclined plane with thesupport plate. The support plate can thus also be connected to themounting by means of at least four spindle drives, whereby an evengreater number of valve pins can be displaced simultaneously.

In some embodiments of the invention the thrust rods are designed asgear racks and the rotary elements as gear pinions engaged with same.Even more compact dimensions are thus enabled with the actuating device.

In some embodiments of the invention, each individual rotary element isconnected to its respectively associated thrust rod at a point distancedfrom its axis by means of a slotted guide system and/or a pivot bearingextending transverse to the sliding direction. The actuating device canthus be manufactured economically.

In some embodiments of the invention the motion converter devices areconfigured as ball screws. The support plate can then be displaced atlow friction. This is particularly advantageous in the case of a largersupport plate displaced by just one electric motor.

In some embodiments of the invention, the rotary elements are arrangedbetween the thrust rods. The space between the rotary elements can thenbe used for the mounting so that it can be of correspondingly stableconfiguration.

In some embodiments the individual ball screws each comprise arecirculating ball spindle fixedly connected to the support plate and arecirculating ball nut arranged thereon which is rotatably mounted tothe mounting about its axis and non-rotatably fixed to its associatedrotary element. The support plate can then be easily mounted to themounting when the actuating device is assembled or after service ormaintenance work being performed by the support plate plane of extensionfirst being aligned parallel to the mounting or perpendicular to theaxes of the recirculating ball spindles and then screwed to therecirculating ball spindles.

In some embodiments of the invention it is convenient for cooperatingconical centering means to be provided on the recirculating ball spindleon the one hand and on the support plate on the other, whereby theindividual recirculating ball spindles are each screwed to the supportplate by means of a screw or screw nut. The support plate can then beeasily mounted to the recirculating ball spindles by the cooperatingcentering means being respectively positioned so as to lay flat againsteach other. The recirculating ball spindles are then screwed to thesupport plate by the screws and/or screw nuts, whereby the screws and/orscrew nuts are preferably tightened at a predetermined torque. Thecentering means are preferably designed such that all the torque actingon the recirculating ball spindles upon tightening the screws and/orscrew nuts is wholly applied to the support plate so that therecirculating ball spindles cannot turn with the screws and/or screwnuts. Advantageously, the torque acting on the recirculating ballspindles during operation of the actuating device is directly applied tothe support plate by the centering means so that the screws and/or screwnuts cannot disengage.

In an embodiment of the invention, the actuating drive comprises anelectric motor having a stator connected to the mounting and a rotor,wherein the rotor is in drive connection with the sliding mechanism bymeans of a further ball screw. The rotation of the rotor can thereby beconverted into the linear movement at low friction. The electric motorcan particularly be a servomotor and preferentially a torque motor. Ifnecessary, the electric motor can be designed and/or controllable by anapplicable drive control device such that the valve pins can bepositioned into at least one intermediate position disposed betweentheir open and their closed position.

In some embodiments of the invention, the sliding mechanism comprises across bar connecting the first thrust rod and the second thrust rodtogether in a U-shape, wherein the actuating drive engages the cross barto displace the sliding mechanism. This results in a simple andsymmetrical structure in which the linear movement of the actuatingdrive can be uniformly transmitted to the two thrust rods.

In some embodiments of the invention the mounting can comprise at leastone plate or one frame.

-   In accordance with the invention there is provided a hot runner    system (100) for simultaneous injection molding of a plurality of    parts in separate mold cavities (78, 79), comprising:    -   an injection molding manifold (7) having an inlet opening (19)        for receipt of the injection fluid,    -   a plurality of nozzles (8) communicating with one or more flow        channels in the manifold (7), each nozzle having a valve pin (2)        for controlling the flow of melt from the nozzles (8) to one or        more mold cavities (78, 79),    -   a support plate (11) or a support frame that supports the        plurality of valve pins (2) or adjusters for the valve pins (2),        said support plate (11) or support frame being movable along a        first direction in order to simultaneously move the valve pins        (2) or adjusters (86) relative to the one or more mold cavities        (78, 79),    -   an actuator (12) for displacing the support plate (11) or        support frame and for generating a valve pin (2) closing force        along a first direction toward the one or more mold cavities        (78, 79), said actuator (12) comprising a torque generating        structure (59) having an electrical component (32), a rotary        mechanism (34) drivable by the electrical component (32) and a        thrust arm (33) directly coupled to the rotary mechanism (34)        and movable along a second direction (13),    -   a sliding mechanism (14, 15, 16) arranged external of the        actuator (12) coupled to the thrust arm (33) of the actuator        (12), wherein the sliding mechanism (14, 15, 16) is movable        along the second direction (13) and interconnected to a        stationary plate (5, 6) or a stationary frame, wherein the        sliding mechanism (14, 15, 16) comprises rigid components in        order to transmit the closing force along the second direction,    -   an engaging or connecting mechanism (60, 61, 62, 63) directly        interconnected to the sliding mechanism (14, 15, 16) and        comprising at least two separate engaging or connecting        structures (60, 61),    -   a plurality of rotary mechanisms (23, 24, 25, 26) each        comprising at least one rotary element (28, 29) supported on the        stationary plate (5, 6) or stationary frame, wherein the rotary        elements (28, 29) are interconnected to at least two engaging or        connecting structures (60, 61) to convert the linear movement of        the sliding mechanism (14, 15, 16) into a plurality of        simultaneous rotary movements in order to direct the closing        force along the first direction,    -   a reciprocating mechanism (27) fixed to the support plate (11)        or support frame, wherein the reciprocating mechanism (27) is        directly coupled to the rotary elements (28, 29) in order to        effect movement of the support plate (11) or support frame along        the first direction such that a force for simultaneous movement        of the valve pins (2) or adjusters (86) along the first        direction by way of the support plate (11) or the support frame        can be generated by the actuator (12) and transmitted by the        rigid components of the sliding mechanism (14, 15,16) via a        translational movement coupled with rotation to distribute the        closing force to the plurality of rotary elements (28, 29) which        have rotational axes generally coaxial with an axis of the valve        pins (2) or adjusters (86).-   In such a system the actuator (12) is typically comprised of an    electric motor or a drive control device such that the valve pins    (2) can be positioned in at least one third position disposed    between a first position and a second position and can be held as    needed in said third position.-   In such a system the valve pins (2) can include a cylindrical    section at a free end region that is distant or distal relative to    the support plate (11) which interacts with a corresponding valve    seat (77) of a respective hot runner nozzle (8) such that flow    through a nozzle is closed when an associated valve pin is disposed    in either the second position or the third position of the valve    pins (2).-   In such a system the valve pins (2) are typically arranged in the    mold cavities (78, 79) by a free end that is distant or distal    relative to the support plate (11) in the second position and are    arranged completely external of the mold cavities (78, 79) in the    third position.-   In such a system the valve pins (2) preferably each have a section    which tapers, preferably conically or in cone-shaped manner, toward    a free end of the valve pins (2) on a free end region distant or    distal relative to the support plate (11).-   In such a system at least two nozzles (8) preferably have outlet    openings (80) arranged to route injection fluid along different    directions and valve pins (2) that are arranged along different    directions, wherein the valve pins (2) are drivably interconnected    to an adjuster such that the closing force is transmittable from the    adjuster to the valve pins (2).-   In such a system the rotary mechanism (23, 24, 25, 26) can comprise    a sleeve having a helical cam follower slot or a ball nut or a    re-circulating ball nut.-   In such a system the reciprocating mechanism (27) can comprise a    spindle having a helical track and a ball screw.-   In such a system the engaging or connecting mechanism (60, 61, 62,    63) can comprise a gear rack.-   In such a system the engaging or connecting mechanism (60, 61, 62,    63) can comprise a lever arm (44-47, 54-57, 44′″-47′″).-   In another aspect of the invention there is provided a method of    simultaneously molding a plurality of parts from two or more mold    cavities, the method comprising injecting an injection fluid into    the two or more mold cavities in a hot runner system comprised of:    -   an injection molding manifold (7) having an inlet opening (19)        for the injection fluid,    -   a plurality of nozzles (8) communicating with one or more flow        channels in the manifold (7), each nozzle having a valve pin (2)        for controlling the flow of melt from the nozzles (8) to one or        more mold cavities (78, 79),    -   a support plate (11) or a support frame that supports the        plurality of valve pins (2) or adjusters for the valve pins (2),        said support plate (11) or support frame being movable along a        first direction in order to simultaneously move the valve pins        (2) or adjusters (86) relative to the one or more mold cavities        (78, 79),    -   an actuator (12) for displacing the support plate (11) or        support frame and for generating a valve pin (2) closing force        along a first direction toward the one or more mold cavities        (78, 79), said actuator (12) comprising a torque generating        structure (59) having an electrical component (32), a rotary        mechanism (34) drivable by the electrical component (32) and a        thrust arm (33) directly coupled to the rotary mechanism (34)        and movable along a second direction (13),    -   a sliding mechanism (14, 15, 16) arranged external of the        actuator (12) coupled to the thrust arm (33) of the actuator        (12), wherein the sliding mechanism (14, 15, 16) is movable        along the second direction (13) and interconnected to a        stationary plate (5, 6) or a stationary frame, wherein the        sliding mechanism (14, 15, 16) comprises rigid components in        order to transmit the closing force along the second direction,    -   an engaging or connecting mechanism (60, 61, 62, 63) directly        interconnected to the sliding mechanism (14, 15, 16) and        comprising at least two separate engaging or connecting        structures (60, 61),    -   a plurality of rotary mechanisms (23, 24, 25, 26) each        comprising at least one rotary element (28, 29) supported on the        stationary plate (5, 6) or stationary frame, wherein the rotary        elements (28, 29) are interconnected to at least two engaging or        connecting structures (60, 61) to convert the linear movement of        the sliding mechanism (14, 15, 16) into a plurality of        simultaneous rotary movements in order to direct the closing        force along the first direction,    -   a reciprocating mechanism (27) fixed to the support plate (11)        or support frame, wherein the reciprocating mechanism (27) is        directly coupled to the rotary elements (28, 29) in order to        effect movement of the support plate (11) or support frame along        the first direction such that a force for simultaneous movement        of the valve pins (2) or adjusters (86) along the first        direction by way of the support plate (11) or the support frame        can be generated by the actuator (12) and transmitted by the        rigid components of the sliding mechanism (14, 15,16) via a        translational movement coupled with rotation to distribute the        closing force to the plurality of rotary elements (28, 29) which        have rotational axes generally coaxial with an axis of the valve        pins (2) or adjusters (86).

BRIEF DESCRIPTION OF THE DRAWINGS

The following will reference the figures in describing embodiments ofthe invention in greater detail.

FIG. 1: is a top perspective view of an embodiment of a system accordingto the invention showing having actuating device for displacing pinvalves using a common plate.

FIG. 2: is a partial longitudinal sectional view through FIG. 1 showingsome of the plurality of hot runner nozzles mounted in the device.

FIG. 3: is a partial longitudinal sectional view through a systemaccording to the invention, the system showing two of a plurality of hotrunner nozzles.

FIG. 4: is a cross-sectional view through the actuating device of theFIG. 1 system.

FIG. 5: is a partial cross-sectional view through the actuating deviceof the FIG. 1 system showing a ball screw.

FIG. 6: is a top perspective partial view of the actuating device of theFIG. 1 system showing in particular the arrangement and configuration ofracks and ball screws.

FIG. 7: is a partial side view of the actuating device of the FIG. 1system depicting a support plate displaceable by means of electricallydriven gear racks and ball screws and a manifold for melt distributiondisposed downstream of the plate.

FIG. 8: is a partial top plan view of a second embodiment of anactuating device usable in a system according to the invention in whichtwo thrust rods comprising a slotted guide system can drive rotatablymounted levers.

FIG. 9: is a partial top plan view of a third embodiment of an actuatingdevice usable in a system according to the invention.

FIG. 10: is a partial top plan view of a fourth embodiment of anactuating device usable in a system according to the invention.

FIG. 11: is a side schematic view of a motion converter device usable ina system according to the invention comprising a shaft with a cam trackhaving inclined planes.

FIG. 12: is a partial longitudinal sectional view through a hot runnernozzle usable in a system according to the invention as depicted inFIGS. 1-11.

FIGS. 13 through 15: are partial longitudinal enlarged sectional viewsof a distal end of a nozzle usable in a system according to FIGS. 1-12showing the area around the downstream outlet opening of the hot runnernozzle with the valve pin disposed in sequentially different downstreamdriven positions from FIG. 13 to FIG. 15.

FIG. 16: is a side longitudinal sectional view through a hot runnernozzle usable in a system according to the invention as shown forexample in FIGS. 1-12.

FIG. 17: is an enlarged side sectional detail view of the hot runnernozzle shown in FIG. 16 in the area of the outlet opening, wherein thevalve pin of the hot runner nozzle is disposed in a first open position.

FIG. 18: is a view similar to FIG. 17 wherein the valve pin is disposedin a second closed position.

FIG. 19: is a partial side longitudinal sectional view through a hotrunner system according to the invention having hot runner nozzles withoutlet openings pointing in different directions for use in the systemembodiments of FIGS. 1-12.

DETAILED DESCRIPTION

An actuating device for displacing valve pins 2 of a hot runner system100 for a hot runner injection molding apparatus identified as a wholein FIG. 1 by reference numeral 1 exhibits a mounting comprising a stackof plates with a plurality of retaining plates 3, 4, 5, 6 arranged oneflat on top of the other.

A cut-out is provided between a first retaining plate 3 and a secondretaining plate 4 fixedly connected thereto in which a manifold 7 whichis connected to a plurality of hot runner nozzles 8 is arranged. As canbe seen in FIG. 2, the manifold 7 is connected to an inlet opening 10via a feed runner 9 to which an injection nozzle of an injection moldingmachine can be connected which delivers a moldable melt to the manifold7. The manifold 7 has runners leading to the hot runner nozzles 8connected in a manner known per se to the feed runner 9. The melt can beinjected into the mold cavities 78, 79 of an injection mold via hotrunner nozzles 8 (FIG. 3). A separate mold cavity 78, 79 is therebypreferably allocated to each hot runner nozzle 8. The mold cavity 78, 79is formed between mold parts 83, 84 able to be brought into an open anda closed position.

In each hot runner nozzle 8 a respective valve pin 2 of a valve gate isdisplaceably arranged between an open and a closed position in the axialdirection of the hot runner nozzle 8. The flow of the melt can becontrolled by way of the valve pins 2.

All of the valve pins 2 are at a parallel distance from one another andeach connected to a common support plate 11 at an end section distantfrom their associated valve seat 77. The support plate 11 is mounted tothe mounting so as to be displaceable back and forth in the axialdirection of the valve pins 2 relative to the retaining plates 3, 4, 5,6 of the mounting along a first direction 87 for the simultaneousopening and closing of the hot runner nozzles 8. FIGS. 2 and 4 show thesupport plate 11 in its lower position in which the valve pins 2 restagainst the valve seats 77 and the outlet openings 80 of the hot runnernozzles 8 are thus closed.

To shift the valve pins 2 between the open and the closed position, theactuating device 1 has an actuating drive 12 comprising an actuatingelement 58 which can be moved back and forth relative to the retainingplates 3, 4, 5, 6 correspondent with a linear movement in a seconddirection 13 oriented transverse to the axial direction of the valvepins 2, which will hereinafter also be referred to as the slidingdirection 13.

The actuating element 58 is in drive connection with a sliding mechanismcomprising a first thrust rod 14 and a second thrust rod 15 distancedparallel thereto which is mounted to the mounting so as to bedisplaceable back and forth in the sliding direction 13. It can be seenin FIG. 5 that a third retaining plate 5 arranged adjacent to the secondretaining plate 4 comprises a respective dovetail guide 17, 18 for eachthrust rod 14, 15, on which the respective thrust rod 14, 15 isdisplaceably guided.

Another suitable linear guide can also be provided instead of thedovetail guides 17, 18, particularly a recirculating ball bearing guideor a circular guide. The thrust rods 14, 15 are designed as bendingresistant elements.

In the embodiment depicted in FIGS. 1, 2 and 3-6, the thrust rods 14, 15are fixedly connected together by means of a bending resistant cross bar16. The actuating element 58 of the actuating drive 12 engages at thecross bar 16.

The thrust rods 14, 15 are in drive connection with the support plate 11via a reciprocating apparatus.

The reciprocating apparatus comprises a first rotary element 19rotatably mounted about a first axis on a fourth retaining plate 6 ofthe mounting in drive connection with the first thrust rod 14. As can beseen from FIGS. 1 and 4, the first thrust rod 14 is designed as a gearrack and the first rotary element 19 as a gear pinion engaged thereto.

Correspondingly, the reciprocating apparatus has a second rotary element20 rotatably mounted about a second axis parallel to the first axis onthe fourth retaining plate 6 in drive connection with the second thrustrod 15. The second thrust rod 15 is designed as a gear rack and thesecond rotary element 20 as a gear pinion engaged thereto.

The reciprocating apparatus further comprises a third rotary element 21rotatably mounted about a third axis arranged parallel to the first axison the fourth retaining plate 6 in drive connection with the firstthrust rod 14 which is designed as a gear pinion engaged with the firstthrust rod 14.

Correspondingly, the reciprocating apparatus comprises a fourth rotaryelement 2 rotatably mounted about a fourth axis arranged parallel to thefirst axis on the fourth retaining plate 6 in drive connection with thesecond thrust rod 15 which is designed as a gear pinion engaged with thesecond thrust rod 15.

It can be recognized from FIG. 6 that the rotary elements 19, 20, 21, 22are each respectively arranged between the thrust rods. The first axisand the fourth axis as well as the second axis and the third axis arethereby arranged point-symmetrically with respect to an axis of symmetrycoinciding with roughly the central longitudinal axis of the feedrunner.

The first rotary element 19 is in drive connection with the supportplate 11 via a first motion converter device 23, as is the second rotaryelement 20 via a second motion converter device 24, the third rotaryelement 21 via a third motion converter device 25, and the fourth rotaryelement 22 via a fourth motion converter device 26 (FIG. 7). The motionconverter devices 23, 24, 25, 26 are each designed as ball screws whichdeflect the translational motion of the thrust rods 14, 15 by 90° in theaxial direction of the valve pins 2.

Recognizable from FIG. 5 is that the first motion converter device 23comprises a recirculating ball spindle 27 fixedly connected to thesupport plate 11 and recirculating ball nut 28 disposed thereon which isrotatably mounted on the fourth retaining plate 6 about the first axisby means of a first roller bearing 29. Bearing balls not shown in anygreater detail in the figure are arranged between the recirculating ballspindle 27 and the recirculating ball nut 28 which can move alonghelical inclined planes orbiting the recirculating ball spindle 27 whichextend along a closed trajectory at the lateral surface of therecirculating ball spindle 27 and the inner wall of the recirculatingball nut 28.

The recirculating ball nut 28 is non-rotatably fixed to the first rotaryelement 19 which is rotatably mounted to the third retaining plate 5about the first axis by means of a second roller bearing 30.

The configuration of the second, third and fourth motion converterdevices 24, 25, 26 corresponds to the configuration of the first motionconverter device 23, hence the description of motion converter devices24, 25, 26 provided there applies analogously

When the thrust rods 14, 15 by means of the actuating drive aredisplaced in sliding direction 13 relative to the retaining plates 3, 4,5, 6, the rotary elements 19, 20, 21, 22 and the recirculating ball nuts28 of the motion converter devices 23, 24, 25, 26 rotate about theirrespective axes, whereby the recirculating ball spindles 27 and thesupport plate 11 fixedly connected thereto are displaced in the axialdirection of the valve pins 2 relative to retaining plates 3, 4, 5, 6and the valve seats 77 fixedly connected thereto.

It is recognizable from FIG. 5 that an outer cone is provided on therecirculating ball spindle 27 and a corresponding inner cone on thesupport plate 11. The recirculating ball spindle 27 is fixed to thesupport plate 11 by means of a screw 31 at least partially passingthrough the support plate 11 which is screwed to a threaded holepositioned on the face of the recirculating ball spindle 27.

The actuating drive 12 has an electric motor comprising a stator 32connected to the mounting and a rotor not shown in any greater detail inthe figure which drives a further recirculating ball nut 34 of a furthermotion converter device 35 arranged on a further recirculating ballspindle 33. Said recirculating ball nut 34 is axially fixed relative tothe stator 32 so that the recirculating ball spindle 33 is moved insliding direction 13 relative to the mounting when the recirculatingball nut 34 is actuated by the rotor. The rotary movement of the rotoris thereby converted into a linear movement. To control the valve pins2, the electric motor is connected to an electrical drive control devicenot shown in any greater detail in the figure which controls theelectric motor such that the valve pins are positioned in apredetermined first position in the open position and in a predeterminedsecond position in the closed position.

Also thrust rods 14′, 15′ are arranged parallel to each other andconnected together in an approximate U-shape by a cross bar 16′ in theembodiment shown in FIG. 8. By means of an actuating drive not depictedin any greater detail in FIG. 8, the sliding mechanism formed by thethrust rods 14′, 15′ and the cross bar 16′ can be displaced in slidingdirection 13 extending at a right angle to the longitudinal extension ofthe valve pins relative to the mounting.

Converting the translational movement of the thrust rods 14′, 15′ intothe rotational movement of the rotary elements 19′, 20′, 21′, 22′ iseffected by means of a slotted guide system running transverse to thesliding direction 13 which comprises a respective guide slot 36, 37, 38,39 extending transverse to the sliding direction 13 on the thrust rods14′, 15′ for each rotary element 19′, 20′, 21 ‘, 22’ driven by therespective thrust rod 14′, 15′ in which a guide element 40, 41, 42, 43distanced from the axis of the respective rotary element 19′, 20′, 21′,22′ engages in drive connection with the rotary element 19′, 20′, 21′,22′ by means of a lever 44, 45, 46, 47. The rotary elements 19′, 20′,21′, 22′ are each connected to the support plate 11 via motion converterdevices. The motion converter devices can be configured as balls screwsas in the embodiment depicted in FIGS. 1, 2 and 3 to 6.

As can be recognized from FIG. 9, the cross bar 16″ can also bearticulated to the thrust rods 14″, 15″ by means of the respectiveintermediate element 48, 49. A first intermediate element 48 is therebyconnected to cross bar 16″ by means of a first joint 50 and to the firstthrust rod 14″ by means of a second joint 51 distanced from the pivotaxis of the first joint 50. Correspondingly, a second intermediateelement 51 is connected to cross bar 16″ by means of a third joint 52and to the second thrust rod 15″ by means of a fourth joint 53 distancedfrom the pivot axis of the third joint 51. Converting the translationalmovement of the thrust rods 14″, 15″ into the rotational movement of therotary elements 19″, 20″, 21″, 22″ is effected by means of connectingrods 54, 55, 56, 57, each respectively connected at points distancedfrom one another to their associated thrust rods 14″, 15″ on the oneside and to their associated rotary elements 19″, 20″, 21″, 22″ on theother. When the thrust rods 14″, 15″ are moved in sliding direction 13,the distance between thrust rods 14″, 15″ changes.

In a further embodiment of the invention depicted in FIG. 11, the ballscrew is replaced by a cam mechanism. A groove 75 on a rotatable shaft76 exhibits inclined planes 72 which form a cam track.

A truncated conical driver roller 73 which engages in the cam track isrotatably mounted to the inner wall of a follower sleeve 74. Acylindrical driver roller 73 which interacts with complementary inclinedplanes of the cam track can also be provided in place of the truncatedconical driver roller 73. However, the truncated conical driver roller73 prevents increased slippage between driver roller 73 and cam trackand thereby reduces friction.

In the present embodiment, the sliding movement of the sliding mechanism117 effects a rotation of shaft 76 and the translational movement of thefollower sleeve 74 induces an up and down movement of the support plate11 relative to the stationary retaining plate 106 and the mold cavities78, 79.

The thrust rods 14′″, 15′″ are also arranged parallel to one another andconnected together in a somewhat U-shape by a transverse rod 16′″ in theembodiment depicted in FIG. 10. By means of an actuating device notdepicted in any greater detail in FIG. 10, the sliding mechanism formedby the thrust rods 14′″, 15′″ and the cross bar 16′″ can be displaced ina sliding direction 13 running at a right angle to the longitudinalextension of the valve pins relative to the mounting.

Yet there is no direct coupling between the arms 44′″, 45′″, 46′″, 47′″and the sliding mechanism 14′″, 15′″, 16′″. The arms 44′″, 45′″, 46′″,47′″ are continuously pressed against small rollers 68, 69, 70, 71arranged on the thrust rods 14′″, 15′″ by means of spring elements 64,65, 66, 67. The spring elements 64, 65, 66, 67 are in each casesupported at their one end against the respective arm 44′″, 45′″, 46′″,47′″ and at their other end against a bearing point.

This design is also suitable for the cam rotation mechanism shown inFIG. 11. The cam track can thereby exhibit a stepped profile so that asmall movement of the sliding mechanism 14′″, 15′″, 16′″ can be used tomove the support plate 11 by about 3 mm to 10 mm and open the valve pins2 of the hot runner nozzles. In this case, the support plate 11 can be aframe formed of rigid but lightweight tubes/rods (which can be extrudedas applicable). Such a lightweight and rigid frame structure is moreeasily moved by the cam rotation mechanism shown in FIG. 11.

In the embodiment depicted in FIG. 12, the valve pins 2 exhibit acylindrical section 81 on their free end region distant from the supportplate 11 which can be positioned in the outlet opening 80 of the hotrunner nozzle 8. By means of the adjusting device, the valve pins 2 canbe displaced between a first position shown in FIG. 12, in which theoutlet openings 80/hot runner nozzles 8 are fully open, and a secondposition in which the outlet openings 80/hot runner nozzles 8 arecompletely closed. In the second position, the valve pins 2 have beenmoved by stroke H respective the first position toward the mold cavity78, 79. The valve pins 2 can be positioned into one or more intermediatepositions between the first position and the second position incontrolled manner.

Recognizable from FIG. 13 is that to advance the melt into the moldcavities 78, 79, the outlet openings 80 of the hot runner nozzles 8first need to be fully opened by the valve pins 2 being brought into afirst position in which the free ends 82 of the valve pins 2 aredistanced from the valve seats 77. As soon as the mold cavities 78, 79are completely filled with melt, the valve pins 2 are brought into asecond position shown in FIG. 14 in which the cylindrical sections 81 ofthe valve pins 2 close their associated outlet opening 80. The valvepins 2 thereby enter through the outlet openings 80 and their respectivefree ends 82 protrude somewhat over the adjacently disposed wall of themold part 83 into the mold cavity 78, 79. This action results in a cleangate mark on the molded part. After the melt within the mold cavities78, 79 has cooled enough to where the molded parts can be removed fromthe mold cavity 78, 79, the valve pins 2 retract somewhat and arebrought into a third position shown in FIG. 15 in which the cylindricalsections 81 of the valve pins 2 still close outlet opening 80 but thefree ends 82 of the valve pins 2 are no longer protruding into the moldcavities 78, 79. The mold parts 83 are brought into the open position inthis valve pin position and the molded parts are removed from the moldcavity 78, 79.

In the embodiment shown in FIG. 16, the hot runner nozzles 8 are eachdesigned as open injection molding nozzles having a valve pin 2 affixedto the support plate 11, provided with a plurality of pin tips 85 attheir mold-side ends, for example three evenly spaced tips. The pin tips85 are conical shaped and protrude into likewise conical outlet openings80 such that annular gaps result in said outlet openings 80 throughwhich the injection molding material can be injected into the moldcavity 78, 79.

The valve pins 2 can be displaced by moving the support plate 11 in thedirection of their longitudinal extension and can be moved from a firstposition, shown in FIG. 16, into a second position, shown in FIG. 18,toward the mold cavity 78, 79 in order to reduce the annular gap crosssections in the region of the pin tips, the outlet openings 80 providedthere respectively. Upon the valve pins 2 retracting from the secondinto the first position, the annular gaps of outlet openings 80 evengive way to an approximate circular outlet opening 80 after theretraction of the valve pins 2 at the actual inlet into the mold cavity78, 79 which does not become an annular gap again until the pin tips aremoved back into the second position.

In the embodiment shown in FIG. 19, the support plate 11 holds aplurality of rod-shaped adjusting means 86 extending parallel to oneanother and parallel to the first direction 87. As in the previouslydescribed embodiments in which the support plate 11 bears the valve pins2, the support plate 11 in the embodiment shown in FIG. 16 is alsomounted to the mounting to be displaceable back and forth in a firstdirection 87 relative to the retaining plates 3, 4, 5, 6 along saidfirst direction 87 by means of the actuator 12, the sliding mechanism14, 15, 16, the engaging or connecting mechanism 60, 61, 62, 63, therotary mechanisms 23, 24, 25, 26 and the reciprocating mechanism 27. Thefirst direction is thereby disposed parallel to the adjusting means 86.Thus, the statements made with respect to the previously describedembodiments also apply analogously to the embodiment depicted in FIG.16.

Each adjusting means 86 is allocated two respective hot runner nozzles 8arranged on the manifold 7 having outlet openings 80 pointing indifferent directions. As can be seen in FIG. 19, the valve pins 2 ofthese hot runner nozzles 8 point with their free ends in to each otheropposite directions. The valve pins 2 are mounted in the hot runnernozzles 8 to be displaceable to and from the adjusting means 86.

The valve pins 2 are each in drive connection with their associatedadjusting means 86 such that the closing force can be transmitted viathe support plate 11 and the adjusting means 86 to the valve pins 2. Theadjusting means 86 has a respective inclined plane 88 for each of thevalve pins 2 allocated to it at an end region distanced from the supportplate 11, on which the end of said valve pin 2 distanced from the moldcavity 78, 70 associated with said respective valve pin 2 comes to bear.When the valve pins 2 are in their open position and the support plate11 is moved along the double arrow 87 toward the valve pins 2, the valvepins 2 are displaced by the adjusting means 86 and each shifted in thedirection of their closed position.

1. A hot runner system for the simultaneous injection molding of aplurality of parts in separate mold cavities comprising: an injectionmolding manifold having an inlet opening for receipt of the injectionfluid, a plurality of nozzles communicating with one or more flowchannels in the manifold, each nozzle having a valve pin for controllingthe flow of melt from the nozzles to one or more mold cavities, asupport plate or a support frame that supports the plurality of valvepins or adjusters for the valve pins, said support plate or supportframe being movable along a first direction in order to simultaneouslymove the valve pins or adjusters relative to the one or more moldcavities, an actuator for displacing the support plate or support frameand for generating a valve pin closing force along a first directiontoward the one or more mold cavities, said actuator comprising a torquegenerating structure having an electrical component, a rotary mechanismdrivable by the electrical component and a thrust arm directly coupledto the rotary mechanism and movable along a second direction, a slidingmechanism arranged external of the actuator coupled to the thrust arm ofthe actuator, wherein the sliding mechanism is movable along the seconddirection and interconnected to a stationary plate or a stationaryframe, wherein the sliding mechanism comprises rigid components in orderto transmit the closing force along the second direction, an engaging orconnecting mechanism directly interconnected to the sliding mechanismand comprising at least two separate engaging or connecting structures,a plurality of rotary mechanisms each comprising at least one rotaryelement supported on the stationary plate or stationary frame, whereinthe rotary elements are interconnected to at least two engaging orconnecting structures to convert the linear movement of the slidingmechanism into a plurality of simultaneous rotary movements in order todirect the closing force along the first direction, a reciprocatingmechanism fixed to the support plate or support frame, wherein thereciprocating mechanism is directly coupled to the rotary elements inorder to effect movement of the support plate or support frame along thefirst direction such that a force for simultaneous movement of the valvepins or adjusters along the first direction by way of the support plateor the support frame can be generated by the actuator and transmitted bythe rigid components of the sliding mechanism via a translationalmovement coupled with rotation to distribute the closing force to theplurality of rotary elements which have rotational axes generallycoaxial with an axis of the valve pins or adjusters.
 2. The hot runnersystem according to claim 1, wherein the actuator is comprised of anelectric motor or a drive control device such that the valve pins can bepositioned in at least one third position disposed between a firstposition and a second position and can be held as needed in said thirdposition.
 3. The hot runner system according to claim 1 wherein thevalve pins comprise a cylindrical section at a free end region distantor distal relative to the support plate which interacts with acorresponding valve seat of a respective hot runner nozzle such thatflow through a nozzle is closed when an associated valve pin is disposedin either the second position or the third position of the valve pins.4. The hot runner system according to claim 1, wherein the valve pinsare arranged in the mold cavities by a free end that is distant ordistal relative to the support plate in the second position and arearranged completely external of the mold cavities in the third position.5. The hot runner system according to claim 1, wherein the valve pinseach have a section which tapers, preferably conically or in cone-shapedmanner, toward a free end of the valve pins on a free end region distantor distal relative to the support plate.
 6. The hot runner systemaccording to claim 1, wherein at least two nozzles have outlet openingsarranged to route injection fluid along different directions and valvepins arranged along different directions, wherein said valve pins are indrivably interconnected to an adjuster such that the closing force istransmittable from the adjuster to the valve pins.
 7. The hot runnersystem according to claim 1, wherein the rotary mechanism comprises asleeve having a helical cam follower slot or a ball nut or are-circulating ball nut.
 8. The hot runner system according to claim 7,wherein the reciprocating mechanism comprises a spindle having a helicaltrack and a ball screw.
 9. The hot runner system according to claim 1,wherein the engaging or connecting mechanism comprises a gear rack. 10.The hot runner system according to claim 1, wherein the engaging orconnecting mechanism comprises a lever arm
 11. A method ofsimultaneously molding a plurality of parts from two or more moldcavities, the method comprising injecting an injection fluid into thetwo or more mold cavities in a hot runner system comprised of: aninjection molding manifold having an inlet opening for receipt of theinjection fluid, a plurality of nozzles communicating with one or moreflow channels in the manifold, each nozzle having a valve pin forcontrolling the flow of melt from the nozzles to one or more moldcavities, a support plate or a support frame that supports the pluralityof valve pins or adjusters for the valve pins, said support plate orsupport frame being movable along a first direction in order tosimultaneously move the valve pins or adjusters relative to the one ormore mold cavities, an actuator for displacing the support plate orsupport frame and for generating a valve pin closing force along a firstdirection toward the one or more mold cavities said actuator comprisinga torque generating structure having an electrical component, a rotarymechanism drivable by the electrical component and a thrust arm directlycoupled to the rotary mechanism and movable along a second direction, asliding mechanism arranged external of the actuator coupled to thethrust arm of the actuator, wherein the sliding mechanism is movablealong the second direction and interconnected to a stationary plate or astationary frame, wherein the sliding mechanism comprises rigidcomponents in order to transmit the closing force along the seconddirection, an engaging or connecting mechanism directly interconnectedto the sliding mechanism and comprising at least two separate engagingor connecting structures, a plurality of rotary mechanisms eachcomprising at least one rotary element supported on the stationary plateor stationary frame, wherein the rotary elements are interconnected toat least two engaging or connecting structures to convert the linearmovement of the sliding mechanism into a plurality of simultaneousrotary movements in order to direct the closing force along the firstdirection, a reciprocating mechanism fixed to the support plate orsupport frame, wherein the reciprocating mechanism is directly coupledto the rotary elements in order to effect movement of the support plateor support frame along the first direction such that a force forsimultaneous movement of the valve pins or adjusters along the firstdirection by way of the support plate or the support frame can begenerated by the actuator and transmitted by the rigid components of thesliding mechanism via a translational movement coupled with rotation todistribute the closing force to the plurality of rotary elements whichhave rotational axes generally coaxial with an axis of the valve pins oradjusters.